Solar Panels and Heat Pump fitted but savings not as suggested.

jaynexxx_2

We recently received a grant under the eco4 scheme to have solar panels and a heat pump fitted. At the initial assessment we were told that the 12 solar panels would pretty much provide us with free electricity during daylight hours, during the summer months when we don't have the heating on. During the winter it should cover the costs of the heat pump for heating/hot water but not enough to cover the rest of the electricity usage.  However, we are still using quite a bit of electricity during the daytime even on really sunny days. Before we had these we were using around 9-10 kwh per day and are now still using 7-8 kwh from the grid. (5-6 kwh of these are daytime usage) We did previously have gas for the hot water so appreciate our overall usage will go up slightly. 
The 'peaks' during the day do tend to be around shower times at around 1kwh per 5 minute shower (2 per day)

So just trying to work out if this seems about right? Do others with Solar Panels and heat pumps get mostly free electricity during summer daylight hours? Was this over estimated at the initial assessment or could i have a problem somewhere with using the solar energy we are generating. We try and be as energy efficient as possible, we don't use a dryer, or run appliances at the same time. We do appreciate we didn't have to pay for these, so any saving we make is a bonus, but i am really panicking that come winter when we are using the heat pump more for the heating we could end up paying more.  

Any experience with your Solar Panels and heat pumps would be greatly appreciated. 

Slinky

We are new to solar panels, and have batteries and no heat pump, so not experts, but if you're having electric heated showers in the morning before the sun is generating much energy, if you don't have batteries, you will be drawing it off the grid. The only way of stopping this is to have showers when the sun is producing more.  Same thing if you are cooking using electric in the evening when the angle of the sun is naturally producing less. It's a question of optimising your heavy usage to the times when the sun is generating most to get the most benefit, if you don't have batteries to store it.

paul991

thermostatic showers straight from the tank would be a better option depending on your set up with a diverter I have little hot water costs for 9 months a year.Are you getting a good rate for your exports ? 

ABrass

jaynexxx_2 said:

We recently received a grant under the eco4 scheme to have solar panels and a heat pump fitted. At the initial assessment we were told that the 12 solar panels would pretty much provide us with free electricity during daylight hours, during the summer months when we don't have the heating on. During the winter it should cover the costs of the heat pump for heating/hot water but not enough to cover the rest of the electricity usage.  However, we are still using quite a bit of electricity during the daytime even on really sunny days. Before we had these we were using around 9-10 kwh per day and are now still using 7-8 kwh from the grid. (5-6 kwh of these are daytime usage) We did previously have gas for the hot water so appreciate our overall usage will go up slightly. 
The 'peaks' during the day do tend to be around shower times at around 1kwh per 5 minute shower (2 per day)

So just trying to work out if this seems about right? Do others with Solar Panels and heat pumps get mostly free electricity during summer daylight hours? Was this over estimated at the initial assessment or could i have a problem somewhere with using the solar energy we are generating. We try and be as energy efficient as possible, we don't use a dryer, or run appliances at the same time. We do appreciate we didn't have to pay for these, so any saving we make is a bonus, but i am really panicking that come winter when we are using the heat pump more for the heating we could end up paying more.  

Any experience with your Solar Panels and heat pumps would be greatly appreciated. 

Either you were mislead or you misheard. Solar panels won't do that.

When it's daylight in the Summer and not cloudy you'll get power, but in practice you'll only reduce your summer power draw, not eliminate it. I've been averaging 50kWh or so a month with 8kW of panels and a battery. If your panels are generating 1kW of power and you run a 11kW power shower, or have a heat pump generating the hot water, then only 1kW of the power will be from the panels the rest from the grid. If you shower early or late then that's when the panels are at their weakest.

In the winter you generate far less. It won't touch the edges of your heat pump use.

What is the power rating of your panels? Old systems were 250W per panel, now you can go up to 500W per panel, but 400W is typical. That means you could have a 3kW system or a 6kW system.

jaynexxx_2

Slinky said:

We are new to solar panels, and have batteries and no heat pump, so not experts, but if you're having electric heated showers in the morning before the sun is generating much energy, if you don't have batteries, you will be drawing it off the grid. The only way of stopping this is to have showers when the sun is producing more.  Same thing if you are cooking using electric in the evening when the angle of the sun is naturally producing less. It's a question of optimising your heavy usage to the times when the sun is generating most to get the most benefit, if you don't have batteries to store it.

We don't have batteries, but we are having showers, cooking, washing etc during daytime hours, and not all at the same time 

jaynexxx_2

paul991 said:

thermostatic showers straight from the tank would be a better option depending on your set up with a diverter I have little hot water costs for 9 months a year.Are you getting a good rate for your exports ? 

We have a hot water tank as part of the heat pump system, it fills back after every use and I presume reheats it when it cools so there is permanent hot water (I think). We haven't got an export tariff yet I'm in the process of trying to set this up but apparently i need a letter from the DNO which I am still waiting for 

jaynexxx_2

ABrass said:

jaynexxx_2 said:

We recently received a grant under the eco4 scheme to have solar panels and a heat pump fitted. At the initial assessment we were told that the 12 solar panels would pretty much provide us with free electricity during daylight hours, during the summer months when we don't have the heating on. During the winter it should cover the costs of the heat pump for heating/hot water but not enough to cover the rest of the electricity usage.  However, we are still using quite a bit of electricity during the daytime even on really sunny days. Before we had these we were using around 9-10 kwh per day and are now still using 7-8 kwh from the grid. (5-6 kwh of these are daytime usage) We did previously have gas for the hot water so appreciate our overall usage will go up slightly. 
The 'peaks' during the day do tend to be around shower times at around 1kwh per 5 minute shower (2 per day)

So just trying to work out if this seems about right? Do others with Solar Panels and heat pumps get mostly free electricity during summer daylight hours? Was this over estimated at the initial assessment or could i have a problem somewhere with using the solar energy we are generating. We try and be as energy efficient as possible, we don't use a dryer, or run appliances at the same time. We do appreciate we didn't have to pay for these, so any saving we make is a bonus, but i am really panicking that come winter when we are using the heat pump more for the heating we could end up paying more.  

Any experience with your Solar Panels and heat pumps would be greatly appreciated. 

Either you were mislead or you misheard. Solar panels won't do that.

When it's daylight in the Summer and not cloudy you'll get power, but in practice you'll only reduce your summer power draw, not eliminate it. I've been averaging 50kWh or so a month with 8kW of panels and a battery. If your panels are generating 1kW of power and you run a 11kW power shower, or have a heat pump generating the hot water, then only 1kW of the power will be from the panels the rest from the grid. If you shower early or late then that's when the panels are at their weakest.

In the winter you generate far less. It won't touch the edges of your heat pump use.

What is the power rating of your panels? Old systems were 250W per panel, now you can go up to 500W per panel, but 400W is typical. That means you could have a 3kW system or a 6kW system.

Thank you that is helpful. Definitely didn't mishear so starting to think I was misled. I think the system is 3.6kw. 

Hexane

Do others with Solar Panels and heat pumps get mostly free electricity during summer daylight hours?

Ignoring the heat pump (because it's not relevant, it doesn't generate electricity, free or otherwise), yes we get free electricity during daylight hours. This varies between a few hundred watts shortly after dawn - enough to run the house baseload plus a computer and display or LED TV. Up to 6kW on a fiercely sunny day in May or June around noon - enough to run two out of three of a condenser tumble dryer, electric oven on its heating cycle, and a large electric kettle, all simultaneously. Then around 2.5kW at noon on a summer day when it's cloudy but bright, or at 5pm on a sunny June day - enough to run the house baseload plus the heating cycle of either the dishwasher or the washing machine. (Ignore anything you've seen on BBC TV - it's not the spin cycle that consumes most power.) Your generation numbers will be smaller. In the absence of battery storage, doing any of these activities at a time when your solar panels are not generating sufficient to wholly power them, means you will be importing electricity from the grid, which means you pay.

This is where human behaviour comes into it. Most people don't wait until 11am to boil the kettle. Or only boil the kettle when the sun comes out. (But, on this forum at least, some people do.) If you get up at 8am and feel like a cup of tea and your kettle consumes 3kW (not all kettles do...) and you don't have battery storage, you have no way out of paying extra for power imported from the grid. You could prepare your tea with a microwave, but an 800W microwave consumes around 1600W (yes really) so there's still a problem.

From your figures, it sounds like your shower is consuming about 12kW instantaneous power. Which means it's heating the water using (lots of) electricity, and that leads me to wonder, isn't it supposed to be your heat pump that's heating the domestic hot water? We have a power shower, but it's from a tanked system (heated by genuinely free surplus solar power using myenergi eddi) with a pump (providing the "power" part) and running at full power it only consumes 600W.

During the winter it should cover the costs of the heat pump for heating/hot water but not enough to cover the rest of the electricity usage.

This sentence is confusing. There's no way that a system with 12 solar panels (even if they're very high output ones, which I suspect yours aren't) is going to provide enough power in winter to make heat pump usage not require grid import. There's also no way, unless some weird Octopus tariff results in you receiving massive payments per kWh generated, that it will result in payments during the winter sufficient to pay for cost of imported electricity for the heat pump.

What I suspect the sentence might mean, is that over the course of a year, on average, the earnings from exported electricity from the 12 solar panels, is expected to cover the cost of the electricity you'll need to import to run the heat pump. This is optimistic too, but it's at least plausible. Most of the earnings will be generated from April to August.

Which means it comes back to paul991's question, what are you getting paid for your exported electricity? And, how much electricity are you exporting at the moment (when your exports should be relatively higher)?

paul991

have you a smart meter if you have i take it your waiting for a export mpan number maybe worth chasing it up . may take up to 4 weeks

markin

A lot of power can be saved by setting the heat pump up 'correctly', Set hot water temp to 43-45c turning off any boost element, Heating water only between 11am and 3pm the warmest part of the day.

The legionnaires cycle to 60c only needs to be every 7 days and is usually separate from the boost element.

Some heatpump models have a terrible 'doing nothing' power draw, So people are turning them off and manually turning on once a day, or every other day for low users just for the hot water over summer.

jaynexxx_2

paul991 said:

have you a smart meter if you have i take it your waiting for a export mpan number maybe worth chasing it up . may take up to 4 weeks

Yes we have a smart meter. From what I understand our installer informs the DNO of the installation and we have to wait for a letter off them before we can apply for the export tariff